Maintenance precautions for customized rotary tube furnaces in multiple temperature zones

As a high-precision heat treatment equipment, customized rotary tube furnaces with multiple temperature zones require maintenance that takes into account core modules such as temperature control, mechanical transmission, atmosphere sealing, and electrical systems. The following are detailed maintenance precautions, covering daily maintenance, regular inspections, and safety operation standards:

1. Daily maintenance: the foundation of preventive maintenance
Furnace body cleaning
Powder residue cleaning: After each experiment, use a vacuum cleaner or soft bristled brush to remove the powder residue in the furnace to avoid long-term accumulation that affects heat conduction efficiency. For oily or viscous substances, a dust-free cloth dipped in alcohol can be used for wiping, and the use of corrosive solvents is prohibited.
Maintenance of furnace tube inner wall: Regularly inspect the inner wall of the furnace tube. If carbon deposition or oxidation layer is found, a special cleaning agent (such as alumina polishing paste) should be used in conjunction with a soft cloth to wipe and restore the smoothness of the inner wall, reducing the risk of sample contamination.
Sealing inspection
Flange connection: Check the connection bolts between the furnace tube and the flange weekly for looseness, and use a torque wrench to tighten them to the standard torque (such as the recommended torque for M12 bolts is 50-60N · m).
Observation window sealing: Check whether the rubber sealing ring of the observation window is aging or deformed. If cracks appear, replace it immediately to prevent air leakage from affecting the accuracy of atmosphere control.
Lubrication of rotating mechanism
Lubricating grease for bearings: High temperature lubricating grease (such as molybdenum disulfide based grease) should be added to the rotating bearings every month, with an appropriate amount to cover 1/3 of the bearing balls, to avoid excessive oil overflow and pollution of the furnace.
Belt tension adjustment: If the equipment uses belt transmission, the belt tension should be checked monthly and adjusted to the manufacturer’s recommended value (such as 50-70N) using a tension meter to prevent the belt from slipping or breaking.

2. Regular maintenance: ensure stable equipment performance
Heating system calibration
Thermocouple calibration: Use standard thermometers (such as platinum rhodium 10 platinum thermocouples) to calibrate thermocouples in each temperature zone every quarter, ensuring that the temperature measurement error is ≤± 1 ℃. If the deviation exceeds the standard, it is necessary to replace the thermocouple or adjust the parameters of the temperature controller.
Heating element inspection: Check the heating resistance wire for oxidation or breakage every six months, use a multimeter to measure the resistance value, and replace the element if the resistance deviation exceeds ± 10%. For vulnerable parts such as silicon molybdenum rods, it is recommended to reserve spare parts to shorten downtime.
Atmosphere system maintenance
Gas pipeline cleaning: Blow the gas pipeline with high-pressure gas every six months to remove impurities and moisture, prevent blockage of the gas path or affect gas purity. For reactive gas (such as H ₂, Cl ₂) pipelines, it is necessary to replace them with inert gas (such as N ₂) and clean them.
Vacuum pump maintenance: Replace the vacuum pump oil (such as F4-68 # vacuum pump oil) every month, check the pump body temperature (normal ≤ 60 ℃), and if the temperature is too high, clean the pump chamber or replace the oil seal.
Mechanical component maintenance
Balance of rotating mechanism: Disassemble the rotating mechanism annually, check the wear of components such as shaft sleeves and gears, and perform dynamic balance correction if necessary to ensure that the vibration amplitude during rotation is ≤ 0.5mm.
Furnace support structure: Check if the furnace support feet are level, adjust with a spirit level to an error of ≤ 0.1 °, to prevent uneven stress on the furnace tube caused by tilting of the furnace body and cracking.

3. Key component replacement cycle: Extend equipment lifespan
List of vulnerable parts
Sealing ring: It is recommended to replace the rubber sealing ring every 1-2 years, and the fluororubber sealing ring can be extended to 3 years (with better high temperature resistance).
Thermocouples: K-type thermocouples have a lifespan of about 2-3 years, while S-type or B-type thermocouples can last for more than 5 years, depending on the operating temperature and atmospheric environment.
Heating element: The lifespan of silicon molybdenum rod is about 2000-3000 hours, and the lifespan of silicon carbon rod is about 1000-2000 hours. It needs to be replaced in advance according to the actual usage time and oxidation degree.
Spare parts Management
Establish a spare parts inventory ledger to record spare parts models, quantities, storage dates, and replacement records. Prioritize the use of spare parts that are stored first to avoid expiration and failure of spare parts.
Reserve commonly used spare parts (such as thermocouples, sealing rings, heating elements) to ensure quick replacement in case of failure and shorten downtime.

4. Safety Operation Standards: Preventing Potential Risks
Pre operation inspection
Confirm that the furnace door is tightly closed and the sealing ring is not damaged to prevent air leakage from causing experimental failure or safety accidents.
Check if the gas valve is closed to avoid the risk of explosion or poisoning caused by accidental ventilation.
Monitoring during the experiment
Regularly observe the temperature curve and atmosphere pressure. If there are abnormal fluctuations (such as temperature exceeding limits or pressure drops), immediately stop the machine for inspection.
It is prohibited to touch high-temperature components (such as furnace tubes and flanges) while the furnace is running. Insulated gloves and protective goggles must be worn.
Post experimental processing
After the experiment is completed, inert gas is first introduced to atmospheric pressure, and then the furnace door is opened to prevent damage to the furnace tube due to internal and external pressure differences.
After the furnace body cools to room temperature, turn off the power and gas source, clean the experimental site, and keep the equipment clean.

5. Long term shutdown maintenance: prevent equipment performance degradation
Furnace protection
Before long-term shutdown, the furnace temperature should be raised to 200 ℃ and kept warm for 2 hours to remove adsorbed moisture and impurities, and then naturally cooled to room temperature.
Place desiccants (such as silica gel) in the furnace to prevent rusting of metal parts or aging of insulation materials in humid environments.
Electrical system protection
Disconnect the main power switch and cover the equipment with a dust cover to prevent dust from entering the electrical control cabinet and causing a short circuit.
Regularly (every 3 months) power on the equipment for 1-2 hours to drive the motor and heating element to avoid long-term idle that may cause component jamming or performance degradation.